An ionizer is often used in the passenger compartment of a motor vehicle for adding negative ions to the air therein. Such an ionizer typically comprises an emitter that can strongly accelerate electrons in an inhomogeneous electrical field to such an extent that they emit and ionize gas molecules of the ambient air, and a high-voltage supply to which the emitter is connected and that can generate the high voltage required for accelerating the electrons in the inhomogeneous electrical field.
A corresponding ionizer comprising an emitter and an electronics box is known from DE 10 2010 056 051. In this known ionizer, the emitter is connected to the electronics box by a connection configured as a connecting line and is spatially separated therefrom. For this purpose, plug connectors are sometimes provided between the emitter that is separated from electronic box and the electronic box.
If these plug connectors between emitter and electronics box are not properly interlocked or have become detached over time, this remains unnoticed. Furthermore, it is not possible to detect whether and to what extent the emitter is damaged or functions properly. Such observations can only be detected with a complex ion measurement that would have to be carried out in the space to be charged with the negative ions.
Furthermore, when operating such ionizers for charging air with negative ions there are inpredictabilities in that ion generation depends on different environmental conditions that occur during operation of such an ionizer, for example on air temperature, humidity, but also on the particle concentration in the air to be charged with negative ions. Here, a multiplicity of mutual and complicated interdependencies occur that can be taken into account only with great difficulty during the operation of such ionizers. Thus, known ionizers of this kind operate with fixed or predetermined high voltages at the emitter. The value of the fixed high voltage is usually selected such that generation of negative ions is ensured under all conceivable environmental conditions of the emitter. Measurements have shown that when significantly exceeding the high voltage level that is required for generating negative ions, ozone is also generated as an undesirable by-product by such ionizers, and the generation rate of ozone increases significantly with increasing high voltage level at the emitter. A voltage level at the emitter significantly above the voltage level required for generating negative ions is therefore disadvantageous and, moreover, due to the accompanying amount of ozone generated at the same time, it presents a health risk.